Droid 3 Digitizer Replacement Help

I ordered two different digitizers from two separate companies. I followed a video online exactly, however, when I plug in the phone the screen lights up with a very faint light but nothing more. I tried both digitizers at least four times but haven't progressed past this point. I saw somewhere in a post about ensuring the sensors are left uncovered otherwise the phone will never turn on. Could that be it, or could it possibly be something different? If it is that, then what sensors are these? But if it isn't, then what else would be the issue? Please help.